1. Field of the Invention
The present invention generally relates to miniature time-of-flight mass spectrometers (TOF-MS) for improving resolution and mass range employing an impulse extraction ion source and methods for its use.
2. Description of the Related Art
Miniature time-of-flight mass spectrometers (TOF-MS) have the potential to be used in numerous field-portable and remote sampling applications due to their inherent simplicity and potential for ruggedization. However, these miniature time-of-flight mass spectrometers traditionally suffer from low mass resolution due to the reduced drift length of the analyzer. Attempts have been made to recover this reduction in mass resolution, by using, for example, ion reflectors. Typically, though, ion reflectors exhibit a limited useful mass range, typically less than 5 kDa. While this range is useful for many biological agents, a much wider mass range is required to detect intact proteins and numerous biological warfare agents. To this end, several forms of “pulsed extraction (PE)” or “delayed extraction” techniques have been developed to reduce the peak widths of ions detected in the TOF analyzer. These methods, however, improve the resolution for only a fraction of the total mass spectrum for any given delay setting thereby requiring the TOF analyzer to be scanned in order to achieve good resolution across a broad mass range.
A need therefore exists for an apparatus and method that does not require the TOF analyzer to be scanned in order to achieve good resolution across a broad mass range.